Breast cancer is one of the most pernicious diseases in women. This disease, which is the most common cancer of women in the Western world and which now attacks one woman in 13, has had a stationary death rate for many years in spite of advances in surgical techniques, radiotherapy and chemotherapy. Statistics show that about 50% of the women succumb to it, in general from the so called metastases.
Therapy of cancer can have much better success the earlier the cancer is detected. Furthermore surgery can be minor if detection is early, avoiding much suffering. It is known that our present methods of surgery, radiotherapy and chemotherapy are effective for long-term survival if applied when the disease is localized to the breast. Since many of the breast cancer cases are not localized when first seen by the clinician, a way must be found to have women present themselves for examination with their disease at an earlier stage than is commonly the case. This means, in a practical way, detection of preclinical cancer in apparently "well" women, when the disease is unsuspected by patient or physician as is the case in mass screening.
There are usually two steps in the diagnosis of breast cancer. First the detection of a lesion by a screening method or by self-detection, and then narrowing down the diagnosis, first by non-invasive methods and finally by biopsy, which when positive, is mostly followed by immediate surgical intervention. Such factors as time of examination, radiation dose or cost of the study assume minor roles when evaluating a lesion which has already been detected.
In screening for breast cancer, a large number of women, who presumably have no disease or have only minimal symptoms, are involved in the program. These women would not be having the examination, were it not for the opportunity offered by the screening program. The major thrust in screening is not, therefore, differential diagnosis of a lesion, but the step preceding that, i.e. the detection of an abnormality. All one does in mass screening must be directed to the following objective: the initial detection of an abnormality in the simplest, safest, most accurate and most economical manner possible.
At present the following methods are used for the detection of breast cancer in most clinics: (1) Clinical examination including: a. Manual palpation; b. Appearance of the skin; c. Deformation of the breast; (2) X-rays (there are several variants available); (3) Thermography; (4) Transillumination; (5) Ultrasonics.
None of these methods is satisfactory by itself, neither are combinations of these methods fully satisfactory. Cancerous tumors are detected in most cases when several years old. It should also be added that final and reliable diagnosis is only done by biopsy. In many institutions positive diagnosis is obtained in only 25% of biopsies done. It seems therefore obvious that better physical methods for screening of a large number of patients as well as more reliable diagnosis before biopsy would be very important. These methods should also be comfortable and not induce some hesitation in women to visit periodically the clinic. They should also be repeatable any number of times and should not encompass even small health hazards (as X-rays do). The present technology and the large number of patients involved make computer aided devices methods of choice.
Of the presently used methods only thermography lends itself to computerized automation. Success is limited, however, by the rather small number of tumors that cause a rise in temperature of the skin.
U.S. Pat. No. 4,291,708 which is hereby incorporated by reference in its entirety, discloses an apparatus for detecting tumors in living human breast tissue comprising: a device for determining the dielectric constants of a plurality of localized regions of living human breast tissue including a balancing bridge having means for automatically nulling the balancing bridge while in operation; a device for measuring variations in dielectric constants over a plurality of regions and for indicating the possible presence of a tumor as a result of the measurement, a device for applying a swept frequency signal to the probe, and signal processing circuitry, coupled to the balancing bridge for providing an output indication of dielectric constant of the localized region of breast tissue associated with the probe.
U.S. Pat. No. 4,458,694, which is he by reference in its entirety, discloses an apparatus for detecting tumors in living human breast tissue comprising: (a) a device for determining the dielectric constants of localized regions of living human breast tissue including a probing component comprising a multiplicity of probe elements; (b) a device for applying an AC signal to the tissue; and (c) a device for sensing electrical properties at each of said probe elements at a plurality of different times; and (d) signal processing circuitry, coupled to said sensing device for comparing the electrical properties sensed at the plurality of different times for providing an output indication of the dielectric constant of the localized region of breast tissue associated with said probing component.
The probe elements are applied to human breast tissue in vivo, such that individual ones of said probe elements are arranged for sensing characteristics of individual localized regions of human breast tissue.
We have now discovered that when the probe elements have an hexagonal structure, much better results are obtained with the diagnosis made by use of the apparatus described in the above patents.